Piston control mechanism for waterless gas storage tank



Feb. 25, 1969 SABURO KANO ET AL 3,429,675

PISTON CONTROL MECHANISM FOR WATERLESS GAS STORAGE TANK Filed Nov. 25, 1964 FIG. 3

INVENTORS SABURO KANO YOSHIO YAMADA SHIGEO WATANUKI ATTORNEYS United States Patent 8/ 63,194 US. Cl. 48-176 8 Claims Int. Cl. F17b 1/16 ABSTRACT OF THE DISCLOSURE Mechanism for maintaining the piston of a waterless gas storage tank substantially level at all vertical positions by the provision of suspension means including cables or the like attached to the piston at a plurality of spaced points, the cables being wound on drums carried by interconnected shafts so as to Wind up or unwind equal lengths of cable simultaneously on or from each drum as the vertical position of the piston is varied.

This invention relates to a waterless gas storage tank. In the gas storage tanks of the conventional type, in which the leaking of the gas is prevented by an oil seal, an inclined piston has a serious effect upon the sealing equi ment (when the piston is inclined, the oil on the raised side goes circumferentially down to the lower side and the depth of seal oil on the raised part might not be enough to prevent gas under the piston to go up through the clearance between the piston and the casing), and the proper performance of the tank might be interfered with: therefore, in order to prevent the piston 3 from being inclined, generally a few sets of guide wheels of two different heights, upper and lower, are provided along the outer circumference of the piston 3, as shown in FIG. 1. Accordingly, the accuracy of the inner dimension of the shell of the tank is required to be very strictly maintained. It must be said, however, that it is very difficult to keep the piston 3 perfectly level, because of the errors in construction work and of the heat expansion of the casing in summer.

The present invention, taking these circumstances into consideration, is to provide a waterless gas storage tank, the sealing of which can be kept perfect by hanging the piston and keeping it always level.

One embodiment of the present invention will be explained hereafter with reference to FIG. 2 and FIG. 3.

FIG. 2 is a vertical section of an embodiment of the waterless gas-holder of the present invention.

FIG. 3 is a cross section along line 3--3 in FIG. 2.

1 is a tank shell, 2 is a fixed roof truss having an inner floor 2', 3 is a piston; cable anchor fittings 4 are provided at three points on the outer circumference of the piston 3 having equal distance between each other; a plural number of guide rollers 5, which roll upon the inner surface of the shell 1, are mounted on the cable anchor fittings 4; wire ropes on cables 6, one end of which is fastened to each fitting 4, extend vertically upward and are reeled onto the rope drums 7 supported by the inner floor 2' of the roof truss 2; and the piston 3 is hung level by the proper initial adjustment of the cables 6.

Each transmission shaft 8 of the rope drums 7 is extended toward the centre of the roof truss 2, so that the bevel gear 9 fixed on the inner end of each transmission shaft 3,429,675 Patented Feb. 25, 1969 8 may be interlocked with the bevel gear 11 mounted at the end of the shaft of the torque motor 10 installed at the center of the roof truss. 12 in the figures shows sealing facilities.

The waterless gas storage tank of the present invention is constituted as explained above; and so it is a matter of course that the piston 3 can be kept level, being hung by the cable 6, when it is at rest. That is, the piston 3 is kept at rest, the weight of the piston 3 itself being balanced with the pressure of the gas put in under the said piston. Even if the piston 3 tends to be inclined, its position can be corrected to keep level automatically, the cable on the rising side being slackened and the cable on the falling side being tightened.

When, both in falling and rising time, there is some unbalance in the friction force on the outer circumference of the piston 3, due to the friction between the contact surfaces of the casing wall 1 and the piston 3, the piston 3 tends to be inclined. When the tension of the cable 6 on the low side is bigger than the unbalance in the friction force, the cable 6 will lfOllOW the movement of the piston 3 by the revolution of the rope drum 7 and will always keep the piston 3 level, thus making the sealing facilities effective. Therefore, the accuracy of the inside surface of the casing may be only in such a degree as not to interfere with the sealing function, and only a few guide rollers 5 in one line may be sufficient for preventing the piston 3 from inclining to one side. This means a big saving in the expense of construction because the height of the shell can be made minimum and structures for upper guiderollers is not necessary.

While, in the foregoing example, rope drums are revolved by one torque motor, the object of the present invention may still be fulfilled, without doubt, by giving a turning effort with a spiral spring along the direction in which cables are wound, to the vertical shaft or the transmission shaft in the center.

What we claim is:

1. A waterless gas storage tank having a cylindrical shell, a piston vertically :movable in said shell and suspension means for said piston, the suspension means com prising at least three rotatable shafts fixedly supported in the tank above the piston, elongated lifting elements fixed to the piston at their lower endsand each extending to a point adjacent a respective rotatable shaft, means on each shaft coacting with the respective lifting element to raise or lower said element upon rotation of said shaft, and drive means interconnecting all said shafts for rotation simultaneously in equal amounts to raise or lower said elements equal distances.

2. A waterless gas storage tank according to claim 1, in which the elongated lifting elements are cables and the coacting lifting means on each shaft are cable drums on which said cables can be wound.

3. A waterless gas storage tank according to claim 1, in which the drive means includes a gear on each shaft and a drive gear in engagement with all said shaft gears.

4. A waterless gas storage tank according to claim 3, in which said gears are bevel gears.

5. A waterless gas storage tank according to claim 3, which includes a motor drivingly connected to said drive gear.

6. A waterless gas storage tank according to claim 2, in which the drive means includes a gear on each shaft and a drive gear in engagement with all said shaft gears.

7. A waterless gas storage tank according to claim 6, in which said gears are bevel gears.

3 8. A waterless gas storage tank according to claim 6, which includes a motor drivingly connected to said drive gear.

References Cited UNITED STATES PATENTS 4 FOREIGN PATENTS 168,818 3/1906 Germany.

JAMES H. TAYMAN, 111., Primary Examiner.

U.S. C1. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,429,675 February 25, 1969 Saburo Kano et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 44, endsand" should read ends and Signed and sealed this 31st day of March 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer WILLIAM E. SCHUYLER, JR. 

